Science Musings Blog

Friday, September 05, 2008

A soggy undertaking

Here, hidden in the ferns and nettles along our ancient track, is a bench mark from the 19th-century survey of Ireland, the epic adventure of mapmaking at the time -- the entire island on a scale of six inches to the mile, including every building and field boundary. The bench marks were cut into walls, or buildings, or even natural stones. They are called "crows feet," or in Irish Lapa na circe, "the hen's foot."

It is hard to get one's head around this ambitious undertaking: Starting with a precisely measured baseline on the banks of Lough Foyle, laying out of a web of triangles across Ireland, from mountain top to mountain top, then ever smaller webs of triangles, ultimately defining fields and the boundaries of townlands. All by hand, in all weathers. A colossal amount of calculation, without benefit of modern computational devices. The resulting maps are things of great beauty; I have examined some of them in their great folio volumes in the University of Cork Library. What is remarkable is how little the field boundaries have changed. The maps are still used in property transactions.

Every time I pass this particular "crow's foot" I think of those intrepid mappers, lugging their theodolites around muddy country roads and bogs, trying to take notes in damp notebooks, rain drops dripping from their beards. And here I sit in my snug little house with satellite images from Google Earth popping up on my computer.